/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package studio.raptor.sqlparser.visitor.functions;

import static studio.raptor.sqlparser.visitor.SQLEvalVisitor.EVAL_VALUE;
import static studio.raptor.sqlparser.visitor.SQLEvalVisitor.EVAL_VALUE_NULL;

import java.math.BigDecimal;
import java.math.BigInteger;
import studio.raptor.sqlparser.ast.SQLExpr;
import studio.raptor.sqlparser.ast.expr.SQLMethodInvokeExpr;
import studio.raptor.sqlparser.util.Utils;
import studio.raptor.sqlparser.visitor.SQLEvalVisitor;
import studio.raptor.sqlparser.visitor.SQLEvalVisitorUtils;

public class OneParamFunctions implements Function {

  public final static OneParamFunctions instance = new OneParamFunctions();

  public static String soundex(String str) {
    if (str == null) {
      return null;
    }
    str = clean(str);
    if (str.length() == 0) {
      return str;
    }
    char out[] = {'0', '0', '0', '0'};
    char last, mapped;
    int incount = 1, count = 1;
    out[0] = str.charAt(0);
    // getMappingCode() throws IllegalArgumentException
    last = getMappingCode(str, 0);
    while ((incount < str.length()) && (count < out.length)) {
      mapped = getMappingCode(str, incount++);
      if (mapped != 0) {
        if ((mapped != '0') && (mapped != last)) {
          out[count++] = mapped;
        }
        last = mapped;
      }
    }
    return new String(out);
  }

  static String clean(String str) {
    if (str == null || str.length() == 0) {
      return str;
    }
    int len = str.length();
    char[] chars = new char[len];
    int count = 0;
    for (int i = 0; i < len; i++) {
      if (Character.isLetter(str.charAt(i))) {
        chars[count++] = str.charAt(i);
      }
    }
    if (count == len) {
      return str.toUpperCase(java.util.Locale.ENGLISH);
    }
    return new String(chars, 0, count).toUpperCase(java.util.Locale.ENGLISH);
  }

  private static char getMappingCode(String str, int index) {
    // map() throws IllegalArgumentException
    char mappedChar = map(str.charAt(index));
    // HW rule check
    if (index > 1 && mappedChar != '0') {
      char hwChar = str.charAt(index - 1);
      if ('H' == hwChar || 'W' == hwChar) {
        char preHWChar = str.charAt(index - 2);
        char firstCode = map(preHWChar);
        if (firstCode == mappedChar || 'H' == preHWChar || 'W' == preHWChar) {
          return 0;
        }
      }
    }
    return mappedChar;
  }

  private static char map(char ch) {
    String soundexMapping = "01230120022455012623010202";
    int index = ch - 'A';
    if (index < 0 || index >= soundexMapping.length()) {
      throw new IllegalArgumentException("The character is not mapped: " + ch);
    }
    return soundexMapping.charAt(index);
  }

  public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
    if (x.getParameters().size() == 0) {
      return SQLEvalVisitor.EVAL_ERROR;
    }

    SQLExpr param = x.getParameters().get(0);
    param.accept(visitor);

    Object paramValue = param.getAttributes().get(EVAL_VALUE);
    if (paramValue == null) {
      return SQLEvalVisitor.EVAL_ERROR;
    }

    if (paramValue == EVAL_VALUE_NULL) {
      return EVAL_VALUE_NULL;
    }

    String method = x.getMethodName();
    if ("md5".equalsIgnoreCase(method)) {
      String text = paramValue.toString();
      return Utils.md5(text);
    }

    if ("bit_count".equalsIgnoreCase(method)) {
      if (paramValue instanceof BigInteger) {
        return ((BigInteger) paramValue).bitCount();
      }

      if (paramValue instanceof BigDecimal) {
        BigDecimal decimal = (BigDecimal) paramValue;
        BigInteger bigInt = decimal.setScale(0, BigDecimal.ROUND_HALF_UP).toBigInteger();
        return bigInt.bitCount();
      }
      Long val = SQLEvalVisitorUtils.castToLong(paramValue);
      return Long.bitCount(val);
    }

    if ("soundex".equalsIgnoreCase(method)) {
      String text = paramValue.toString();
      return soundex(text);
    }

    if ("space".equalsIgnoreCase(method)) {
      int intVal = SQLEvalVisitorUtils.castToInteger(paramValue);
      char[] chars = new char[intVal];
      for (int i = 0; i < chars.length; ++i) {
        chars[i] = ' ';
      }
      return new String(chars);
    }

    throw new UnsupportedOperationException(method);
  }


}
